In the prior art, a non-contact power supply system supplies power in a non-contact manner from a power supply device to a power reception device (for example, refer to patent document 1). In a non-contact power supply system of the prior art, to supply power, the power reception device is arranged on the power supplying device at a determined position. Power is supplied from the power supply device to the power reception device only under this condition.
Over these recent years, to improve user convenience, study has been conducted to develop a free layout type non-contact power supply system that allows for the power reception device to be supplied with power by arranging the power reception device at any position on the upper surface (power supplying surface) of the power supply device (for example, refer to patent document 2).
As shown in FIG. 5A, in a free layout type non-contact power supply system, primary coils L1 are arranged in a power supply device 10 along a power supply surface 6 of the power supply device 10. A power reception device 30 includes a secondary coil L2. In FIG. 5A, the secondary coil L2 is directly opposed to a primary coil L1. The primary coil L1 is excited at an operational frequency f1. A change in the magnetic flux from the excited primary coil L1 induces current at the secondary coil L2. The induced current becomes the output power of the power reception device 30. In this manner, electromagnetic induction is used to supply power from the power supply device 10 to the power reception device 30.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-204637
Patent Document 2: Japanese Laid-Open Patent Publication No. 2008-5573